N-hydroxyalkyl quaternary ammonium salts corresponding to the following general formula: ##STR1## are known. See. e.g., U.S. Pat. Nos. 4,040,992 and 4,582,861. The '992 patent discloses that such catalysts can be used to promote the trimerization of isocyanates, and can be used in formulations for producing polyurethanes, polyurethanepolyisocyanurates and polyisocyanurates. The reference does set forth one specific flexible foam formulation based on toluene diisocyanate and a glycerine/propylene oxide polyether (note Example 23), although no properties for the resultant foam are set forth.
In addition, the art has suggested the use of various trimerization catalysts in preparing flexible polyurethane foams. U.S. Pat. No. 4,767,736 describes a catalyst package consisting essentially of a) triethylene diamine, b) 4-(2-dimethylaminoethyl)morpholine, c) N,N,N',N'-tetramethyl-1,2-diamino-2-methylpropane, d) bis(dimethylaminoethyl)ether, and e) an N-hydroxyalkyl quaternary ammonium acid salt. Such a package is described as eliminating cure drift in foams prepared from one type of "filled" polyol. U.S. Pat. Nos. 4,141,862 and 4,902,723 describe the use of 1,3,5-tris(3-dimethyl-aminopropyl)-s-triazine in flexible polyurethane foams.
British Patent 1,389,932 describes the use of trimerization catalysts in general and specifically exemplifies the use of potassium acetate in the production of a flexible foam from conventional polyethers. Finally, in Bechara et al, "Unusual Catalysts for Flexible Urethane Foams", Proc. S.P.I. Annual Urethane Div. Tech. Conf., 1978, pages 24 through 36, trimethyl hydroxyethyl ethylene diamine (Dabco T) and Dabco TL were described as useful in producing flexible foams from filled polyethers.
Flexible and high resilience ("HR") polyurethane foams based on toluene diisocyanate are known. In producing such HR foams, it is common in the art to use "filled" polyols such as i) polymer polyols or ii) dispersions of polyureas and/or polyhydrazodicarbonamides. When such filled polyols are used, however, it is necessary to utilize various crosslinkers, such as diethanolamine, in order to achieve foam stability. Without the use of such crosslinkers, HR foams collapse prior to gel and are accordingly not usable. By stabilizing with crosslinkers, suitable foam products are formed. While such crosslinkers typically improve foam stability and in some cases improve compression set properties, they also adversely affect strength properties, such as tensile strength, tear strength, and elongation.
Various low molecular weight crosslinkers are used in the manufacture of flexible foams. U.S. Pat. No. 3,067,148 describes the use of tetrahydric compounds derived from ethylene diamine and alkylene oxides. U.S. Pat. No. 3,948,825 describes the use of reaction products of methylene dianiline and alkylene oxides. U.S. Pat. No. 4,569,952 describes the use of an addition product of an alkylene oxide and an aromatic di amine and a mixture of the addition product with an alkanolamine. Finally, U.S. Pat. No. 4,845,133 describes flexible polyurea or polyurea polyurethane foams prepared from high equivalent weight amine terminated compounds and crosslinkers and/or chain extenders.
It was an object of the present invention to produce a flexible polyurethane foam from toluene diisocyanate and a filled polyel which foam was at least as stable as those foams produced using conventional cross linkers and which foam had superior strength properties to those foams produced using conventional cross linkers.